This application outlines a 3 year career development plan to insure the principal investigator's long-term goal of attaining research independence in the fields of hemtopoiesis and hematologic malignancies. This proposal will allow the principal investigator to integrate his past experience in AML cell signaling and bioinformatics to a research program studying microRNAs (miRNAs) and their potential contribution to hematopoietic cell lineage-specific differentiation. The principal investigator will acquire the necessary technical expertise in human hematopoietic progenitor cell culture to translate findings made in a human leukemia cell line model of differentiation to human hematopoiesis. This will be accomplished under the mentorship of Dr. Joseph Bertino (Interim Director, CINJ), who has guided the careers of many of today's leaders in oncology and whose laboratory shares similar interests in human hematopoiesis. In addition, the principal investigator will gain expertise in transcription and chromatin analysis under the direction of Dr. Arnold Rabson, Chief of Cancer Genomics and Molecular Oncology at CINJ. To further insure this project's success, Dr. Roger Strair (Director, Heme Malignancies, CINJ) and Dr. Eric Rubin (Chief, Investigational Therapeutics, CINJ) have been enlisted to serve on this proposal's Advisory Committee. This research proposal will focus on the role of miRNAs in hematopoietic cell differentiation through the molecular analysis of transferrin receptor 1 (TfR-1;CD71) as a target of phorbol ester-induced miRNAs. The regulatory circuit responsible for miRNA lineage-specific expression and transcriptional activation will be elucidated by molecular studies of a prototypic TPA-induced miRNA, miR-320. Finally, we will translate our observations to a model system of primary human hematopoiesis by correlating TfR-1 and putative TfR-1 - targeting miRNA expression in lineage-committed human cord blood cultures, and studying the effect of enforced TfR-1-targeting miRNA expression on human primary hematopoietic stem cell fate decisions. Finally, it is our belief that TfR-1 targeting using miRNAs may represent a novel strategy to undermine the proliferative advantage that is the hallmark of the majority of human malignancies and have potential therapeutic applications.